</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (lee @ Jan 6 2003, 07:29 AM)</td></tr><tr><td id='QUOTE'>my experience is that the unmodified and tbe modified give the same reading within acceptible margin of error. Like a third of a stop. I have tested this with several meters including my own.
The manufacturing tolerances applying to Photographic Light Meters are most probably the limiting factors here. Gossen only claims an accuracy of +/- 1/3 "stop" for their UltraPro.
The manufacturers do not provide easy access to that information. Many years ago, I calibrated a Honeywell "1 degree/ 21 Spot" meter (an attempt to use it in an industrial application) and after a monumental struggle, found that the manufacturing tolerance was only +/- 1/2 "stop".
Given all the variables in the process; film speed tolerance; shutter speed and aperature tolerances; and sundry others, I would not really be too concerned over *exact* exposure.